| Title | FAST Observations of an Extremely Active Episode of FRB 20201124A. III. Polarimetry |
| Authors | Jiang, Jin-Chen Wang, Wei-Yang Xu, Heng Xu, Jiang-Wei Zhang, Chun-Feng Wang, Bo-Jun Zhou, De-Jiang Zhang, Yong-Kun Niu, Jia-Rui Lee, Ke-Jia Zhang, Bing Han, Jin-Lin Li, Di Zhu, Wei-Wei Dai, Zi-Gao Feng, Yi Jing, Wei-Cong Li, Dong-Zi Luo, Rui Miao, Chen-Chen Niu, Chen-Hui Tsai, Chao-Wei Wang, Fa-Yin Wang, Pei Xu, Ren-Xin Yang, Yuan-Pei Yang, Zong-Lin Yao, Ju-Mei Yuan, Mao |
| Affiliation | Peking Univ, Dept Astron, Beijing 100871, Peoples R China Chinese Acad Sci, Natl Astron Observ, Beijing 100101, Peoples R China Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China Univ Chinese Acad Sci, Sch Astron, Beijing 100049, Peoples R China Univ Nevada, Dept Phys & Astron, Las Vegas, NV 89154 USA Chinese Acad Sci, CAS Key Lab FAST, NAOC, Beijing 100101, Peoples R China Res Ctr Intelligent Comp Platforms, Zhejiang Lab, Hangzhou 311100, Peoples R China Univ KwaZulu Natal, NAOC UKZN Computat Astrophys Ctr, ZA-4000 Durban, South Africa Univ Sci & Technol China, Dept Astron, Hefei 230026, Peoples R China CALTECH, Cahill Ctr Astron & Astrophys, MC 249 17, Pasadena, CA 91125 USA CSIRO Space & Astron, POB 76, Epping, NSW 1710, Australia Nanjing Univ, Sch Astron & Space Sci, Nanjing 210093, Peoples R China Nanjing Univ, Key Lab Modern Astron & Astrophys, Minist Educ, Nanjing, Peoples R China Yunnan Univ, South Western Inst Astron Res, Kunming 650504, Yunnan, Peoples R China Chinese Acad Sci, Xinjiang Astron Observ, Urumqi 830011, Peoples R China |
| Keywords | FAST RADIO-BURST FREQUENCY-DEPENDENT POLARIZATION EMISSION ROTATION PSRCHIVE BUNCHES PSRFITS |
| Issue Date | 1-Dec-2022 |
| Publisher | RESEARCH IN ASTRONOMY AND ASTROPHYSICS |
| Abstract | As the third paper in the multiple-part series, we report the statistical properties of radio bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode between the 25th and 28th of September 2021 (UT). We focus on the polarization properties of 536 bright bursts with S/N > 50. We found that the Faraday rotation measures (RMs) monotonically dropped from -579 to -605 rad m(-2) in the 4 day window. The RM values were compatible with the values (-300 to -900 rad m(-2)) reported 4 months ago. However, the RM evolution rate in the current observation window was at least an order of magnitude smaller than the one (similar to 500 rad m(-2) day(-1)) previously reported during the rapid RM-variation phase, but is still higher than the one (<= 1 rad m(-2) day(-1)) during the later RM no-evolution phase. The bursts of FRB 20201124A were highly polarized with the total degree of polarization (circular plus linear) greater than 90% for more than 90% of all bursts. The distribution of linear polarization position angles (PAs), degree of linear polarization (L/I) and degree of circular polarization (V/I) can be characterized with unimodal distribution functions. During the observation window, the distributions became wider with time, i.e., with larger scatter, but the centroids of the distribution functions remained nearly constant. For individual bursts, significant PA variations (confidence level 5 sigma) were observed in 33% of all bursts. The polarization of single pulses seems to follow certain complex trajectories on the Poincare sphere, which may shed light on the radiation mechanism at the source or the plasma properties along the path of FRB propagation. |
| URI | http://hdl.handle.net/20.500.11897/668042 |
| ISSN | 1674-4527 |
| DOI | 10.1088/1674-4527/ac98f6 |
| Indexed | SCI(E) |
| Appears in Collections: | 物理学院 科维理天文与天体物理研究所 |
